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nondestructive testing method of wood moisture content based on a planar capacitance sensor model

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Forestry Studies in China 2010年第3期12卷 142-146页

作者： WANG Jue LUO Yue-sheng LIU Shao-gang College of Science Harbin Engineering University Harbin 150001 P. R. China College of Automation Harbin Engineering University Harbin 150001 P. R. China College of Mechanical and Electrical Engineering Harbin Engineering University Harbin 150001 P. R. China

For our research, a new hybrid experimental-computational method is presented. We applied a least squares fitting method （LSFM） to reconstruct the wood moisture content （WMC） from the data measured with a planar capacitance sensor. A boundary element method （BEM） was used to compute the relationship between capacitance and the dielectric constant. A functional relationship between MC and the dielectric constant was identified by LSFM. The agreement of this final computation result with the experimental data indicates that this method can be used to estimate the WMC quickly and effectively with engineering analysis. Compared with popular statistical methods, a large number of experiments are avoided, some costs of testing are reduced and the efficiency of testing is enhanced.

关键词： planar capacitance sensor nondestructive testing wood moisture content boundary element method least squares fitring method

Excitation and Detection of Shear Horizontal Waves with Electromagnetic Acoustic Transducers for nondestructive testing of Plates

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 428-436页

作者： MA Qingzeng JIAO Jingpin HU Ping ZHONG Xi WU Bin HE Cunfu Electric Power Research Institute of Guangdong Power Grid Corporation College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology

The fundamental shear horizontal（SH0） wave has several unique features that are attractive for long-range nondestructive testing（NDT）. By a careful design of the geometric configuration, electromagnetic acoustic transducers（EMATs） have the capability to generate a wide range of guided wave modes, such as Lamb waves and shear-horizontal（SH） waves in plates. However, the performance of EMATs is influenced by their parameters. To evaluate the performance of periodic permanent magnet（PPM） EMATs, a distributed-line-source model is developed to calculate the angular acoustic field cross-section in the far-field. Numerical analysis is conducted to investigate the performance of such EMATs with different geometric parameters, such as period and number of magnet arrays, and inner and outer coil widths. Such parameters have a great influence on the directivity of the generated SH0 waves that arises mainly in the amplitude and width of both main and side lobes. According to the numerical analysis, these parameters are optimized to obtain better directivity. Optimized PPM EMATs are designed and used for NDT of strip plates. Experimental results show that the lateral boundary of the strip plate has no perceivable influence on SHO-wave propagation, thus validating their used in NDT. The proposed model predicts the radiation pattern ofPPM EMATs, and can be used for their parameter optimization.

关键词： electromagnetic acoustic transducers shear-horizontal waves strip plate nondestructive testing

nondestructive testing of Expansive Soil by Digital Image Method

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Nondestructive Testing of Expansive Soil by Digital Image Me...

International Conference on Experimental Mechanics 2008 (ICEM 2008)

作者： Wenwen Liu~1 Wei Wang~1 Renjun Xie~2 Xiaoyuan He~1 1 Department of Engineering Mechanics Southeast University Nanjing China 2 Department of Civil Engineering Nanjing University of Aeronautics and Astronautics Nanjing China

＜正＞Expansive soil,which contains many expansively clay minerals of the non-saturated soil,is a result of alternating of wet and dry environment.The obvious expansion or contraction in volume makes the fierce intens... 详细信息

关键词： nondestructive testing expansive soil slide optical metrology digital image method

Recent developments in photoacoustic imaging and sensing for nondestructive testing and evaluation

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Visual Computing for Industry,Biomedicine,and Art 2021年第1期4卷 50-62页

作者： Sung-Liang Chen Chao Tian University of Michigan-Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong University200240 ShanghaiChina Engineering Research Center of Digital Medicine and Clinical Translation Ministry of Education200030 ShanghaiChina State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University200240 ShanghaiChina Department of Precision Machinery and Precision Instrumentation University of Science and Technology of China230026 HefeiAnhuiChina

Photoacoustic(PA)imaging has been widely used in biomedical research and preclinical studies during the past two decades.It has also been explored for nondestructive testing and evaluation(NDT/E)and for industrial applications.This paper describes the basic principles of PA technology for NDT/E and its applications in recent years.PA technology for NDT/E includes the use of a modulated continuous-wave laser and a pulsed laser for PA wave excitation,PA-generated ultrasonic waves,and all-optical PA wave excitation and detection.PA technology for NDT/E has demonstrated broad applications,including the imaging of railway cracks and defects,the imaging of Li metal batteries,the measurements of the porosity and Young’s modulus,the detection of defects and damage in silicon wafers,and a visualization of underdrawings in paintings.

关键词： Photoacoustic imaging Photoacoustic sensing nondestructive testing nondestructive evaluation Photoacoustic microscopy

Research on nondestructive testing for structural integrity of large oil storage tanks

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Research on nondestructive testing for structural integrity ...

2017远东无损检测新技术论坛

作者： Hu Jiashun Zhang Anshi Sun Wenyong Sun Bingcai Research Department of Safety Technology CNPC Research Institute of Safety & Environment Technology College of Mechanical Storage and Transportation EngineeringChina University of Petroleum

In recent years, the safety accidents of large storage tanks in our country occur frequently, and the safety status of storage tank is worrying. The structural integrity of the main four components, tank foundation, floor, wall and floating plate, are received more attention in engineering. Under the support of the national key research and development program, according to the present situation of the integrity detection technology of large storage tanks, the research on the nondestructive inspection technology of storage tank is carried out in this paper. The key technical development and existing problem of corresponding inspection methods are discussed firstly, and then structural detection technology framework of the large storage tank are established. Finally, the outlook of the detection data fusion are put forward to provide technical support for the construction of the structural integrity management.

关键词： Storage tank nondestructive testing Ground settlement Floor corrosion Tank wall deformation

Research in Teaching Reform of nondestructive testing Course

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Research in Teaching Reform of Nondestructive Testing Course

2012 International Conference Mechatronic Systems and Materials Application(ICMSMA 2012)

作者： Zhi Zeng Ning Tao Lichun Feng Cunlin Zhang Institute of Physics and Electronic Engineering Chongqing Normal University Beijing Key Laboratory for Terahertz Spectroscopy and Imaging Key Laboratory of Terahertz Optoelectronics Ministry of Education Department of Physics Capital Normal University

With the continuous development of modern science and technology, new nondestructive testing technology continues to emergeAs one of the basic technologies of modern industry, nondestructive testing technology in ensuring product quality and project quality is playing an increasingly important role, its quality guardian of the reputation of the industrial sector has been generally recognizednondestructive testing is one important fundamental course for the students in the department of physics or material engineering, etcThe paper analyzes its teaching status based on the characteristics and problems in the teaching process of nondestructive testing courseCombining the analysis and the personal teaching practice, the paper introduces how to reform the teaching methods and improve the quality in the course of nondestructive testing, such as choosing a suitable textbook, inspiring students’ learning interest, organizing the teaching content reasonably, and combining multimedia and board writing, etcAccordingly, students can better comprehend the basics of nondestructive testing, and lay the foundation for further studies.

关键词： nondestructive testing teaching practice teaching methods.

Microwave and Millimeter Wave nondestructive testing for Surface Cracks in Metals

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Microwave and Millimeter Wave Nondestructive Testing for Sur...

ICEMI'2005第七届国际电子测量与仪器学术会议

作者： Zhao Qingling (Yantai University Institute of Science and Technology for OPTO-Electronic Information Yantai 264005 China)

Using open ended rectangular waveguide probe and open ended coaxial probe approach for detecting and evaluating tight surface cracks in metals are summarized in this paper. The fatigue cracks in a rai

关键词： nondestructive testing microwave millimeter wave surface cracks metals.

Application of Nonlinear Lamb Wave Mixing Method for Residual Stress Measurement in Metal Plate

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Chinese Journal of Mechanical Engineering 2023年第1期36卷 211-223页

作者： Jingpin Jiao Li Li Xiang Gao Quan Cheng Cunfu He Bin Wu Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing 100124China

Harmonic nonlinear ultrasound can offer high sensitivity for residual stress measurements;however,it cannot be used for local stress measurements at a point in space and exhibits nonlinear distortions in the experimental system.This paper presents a feasibility study on the measurement of residual stress in a metal plate using a nonlinear Lamb wave-mixing technique.The resonant conditions for two Lamb waves to generate a mixing frequency wave are obtained via theoretical analysis.Finite element simulations are performed to investigate the nonlinear interactions between the two Lamb waves.Results show that two incident A0 waves interact in regions of material nonlinearity and generate a rightward S0 wave at the sum frequency.Residual stress measurement experiments are conducted on steel plate specimens using the collinear Lamb wave-mixing technique.By setting different delays for two transmitters,the generated sum-frequency component at different spatial locations is measured.Experimental results show that the spatial distribution of the amplitude of the sum-frequency component agrees well with the spatial distribution of the residual stress measured using X-rays.The proposed collinear Lamb wave-mixing method is effective for measuring the distribution of residual stress in metal plates.

关键词： Residual stress Lamb wave Collinear wave mixing nondestructive testing Resonant conditions

Quantitative Detection of Corrosion State of Concrete Internal Reinforcement Based on Metal Magnetic Memory

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结构耐久性与健康监测(英文) 2023年第5期17卷 407-431页

作者： Zhongguo Tang Haijin Zhuo Beian Li Xiaotao Ma Siyu Zhao Kai Tong Guangxi Xinxiang Expressway Co. Ltd.Nanning530000China College of Civil Engineering Chongqing Jiaotong UniversityChongqing400074China

Corrosion can be very harmful to the service life and several properties of reinforced concrete structures.The metal magnetic memory(MMM)method,as a newly developed spontaneous magnetic flux leakage(SMFL)non-destructive testing(NDT)technique,is considered a potentially viable method for detecting corrosion damage in reinforced concrete members.To this end,in this paper,the indoor electrochemical method was employed to accelerate the corrosion of outsourced concrete specimens with different steel bar diameters,and the normal components Bz and its gradient of the SMFL fields on the specimen surfaces were investigated based on the metal magnetic memory(MMM)method.The experimental results showed that the SMFL experimental Bz curves are consistent with the analytical results of the theoretical model.Furthermore,the crest-to-trough behavior on the Bz signal curve and its zero-point gradient spacing can more accurately indicate the corroded area’s extent.Then,a magnetic characteristic parameter W based on a large amount of experimental data was established to characterize the degree of corrosion of the steel bars.The magnetic characteristic parameter W is linearly related to the maximum cross-sectional area loss rateof the corroded reinforcement.This paper will lay the foundation for future research on corrosion detection of reinforced concrete structures based on the MMM method and provide a feasible way for non-destructive detection of corrosion independent of the influence of reinforcement diameter and magnetization history.

关键词： Reinforcing steel metal magnetic memory(MMM)method spontaneous magnetic flux leakage(SMFL) nondestructive testing local corrosion